The adhesives/sealants for automobiles are classified according to application parts, and can be divided into five categories: adhesives for automobile body, adhesives for automobile interiors, adhesives for automobile engine chassis, adhesives for automobile parts, and adhesives for automobile manufacturing processes. It is estimated that by 2020, the total demand for various types of bonding and sealing materials in China's automobile industry will exceed 100,000 tons, of which polyurethane adhesives are the most important type of glue. In recent years, the annual demand for polyurethane adhesives in China Increase at an average rate of 30%.
We will share some basic knowledge of windshield auto glass PU sealant in this part.
It is One-component moisture curing polyurethane adhesive.
The process of directly bonding automobile windshield glass to the car body began in the United States in the 1960s. One-component moisture-curing PU adhesive was first developed by ESSEX Chemical Company of the United States in the early 1970s and successfully applied to General Motors of the United States. In 1976, Audi Motors also applied it on Audi C2. Subsequently, Japanese and other European automobile manufacturers have successively adopted the direct bonding process of windshield glass. Due to the simple construction and the use of mechanical sizing, more than 95% of the world's windshield and side window glass are bonded using this adhesive.
One-component moisture-curing PU adhesive contains active -NCO groups, which can react with trace moisture on the surface to be adhered or in the air to cure. One-component moisture-curing PU windshield glass glue is required to be sensitive to moisture, fast curing, and maintain excellent elasticity after curing, and it is required to be single-packaged with good storage stability. It is a product with a higher technical content in automotive adhesives, and it is also the most used variety in China's automotive PU adhesives.
Adopting this glass bonding and sealing technology can tightly integrate the windshield glass and the car body into a whole, increase the rigidity of the car body and the ability to resist torsion, and ensure the sealing effect. Article 212 of the US Federal Automobile Safety Standard (FMVSS) stipulates that when a car collides with a concrete wall at a speed of 50km/h, the bonding integrity rate of the windshield must be above 75%. At present, the United States, Japan, Germany, France, etc. and our country almost all adopt this process in the installation of car windshield glass, and at the same time, most of the windshield and side window glass of passenger cars also adopt the bonding method.
One-component moisture-curing PU sealant is suitable for porous surface bonding. For non-porous surfaces such as glass and metal, it usually needs to be used together with glass activator, glass primer, and paint primer. In order to ensure the reliable bonding performance between the windshield glass and the car body, it is necessary to coat the primer on the glass surface, which can improve the bonding strength of the PU adhesive on the glass layer.
Post time: Nov-09-2021